Wheeler's delayed-choice experiment highlights strange features of quantum theory such as pre-sensing of the experimental setup by the quantum object and the role of time. A recent proposal for such an experiment with an interferometer having a quantum beam splitter (QBS) [R. Ionicioiu and D. R. Terno, Phys. Rev. Lett. 107, 230406 (2011)] and its subsequent experimental implementations through photonics and NMR have produced results including the modification in the concept of complementarity. Here we propose a matter-wave Mach-Zehnder-Bragg cavity-QED interferometric setup with final QBS engineered through a cavity field that is taken initially in the superposition of zero and one photon. The setup operates through first-order off-resonant Bragg diffraction of the neutral atoms from the cavity fields with the matter wave's particle (wave) nature marked through the absence (presence) of a photon in the final cavity. The proposal, addressing the issue through atomic de Broglie waves, can be executed within the present cavity-QED experimental scenario with appreciable success probability and fidelity.

Hyperentangled states have boosted many quantum informatics tasks tremendously due to their high information content per quantum entity. Until now, however, the engineering and manipulation of such states were limited to photonic systems only. In present article, we propose generating atomic hyperentanglement involving atomic internal states as well as atomic external momenta states. Hypersuperposition, hyperentangled cluster, Bell and Greenberger–Horne–Zeilinger states are engineered deterministically through resonant and off-resonant Bragg diffraction of neutral two-level atoms. Based on the characteristic parameters of the atomic Bragg diffraction, such as comparatively large interaction times and spatially well-separated outputs, such decoherence resistant states are expected to exhibit good overall fidelities and offer the evident benefits of full controllability, along with extremely high detection efficiency, over the counterpart photonic states comprised entirely of flying qubits.

The work presents a comparative study of the effects of divalent Ba, Sr, and Pb substituents on the multiferroic properties of BiFeO3. The multiferroic properties of Bi0.75A0.25FeO3 (A = Sr, Pb, Ba) solid solution have been explained taking into account the effects of size differences and electronic configuration differences between the host element (Bi) and the substituent. X‐ray diffraction studies revealed that Sr and Pb substitution at Bi‐site transforms the rhombohedral phase (R3c) to cubic phase (Pm3m), whereas the Ba‐substituted sample exhibited the presence of both rhombohedral and cubic phases (R3c + Pm3m). Electronic structure studies through XPS revealed that charge imbalance induced by divalent substitution was being compensated by the formation of oxygen vacancies, while the Fe ions exist in Fe2+ and Fe3+ states. Replacement of volatile Bi by Sr, Pb, and Ba reduces the concentration of oxygen vacancies (VO2+) and helps to improve the dielectric properties. Strong magnetization enhancement was observed in the substituted compositions and was seen to be consistent with the suppression of cycloid spin structure due to structural transformation as well as possible changes in Fe–O local environment leading to local lattice distortion effects. Furthermore, the observed decrease in the values of magnetic coercivity at low temperature in all the substituted samples is explained in terms of reduced effective single ion anisotropy, originating in the magnetoelectric coupling and being a particularly stronger effect in the case of the lone pair dopant Pb, consistent with theoretical predictions. The lone pair substituent Pb leads to the largest dielectric constant, enhanced magnetization, and large effects on the low‐temperature hysteresis.

The effects of disorder on the structural, magnetic and transport properties of stoichiometric Co2Mn x Ti1−x Al (0 ⩽ x ⩽ 1) thin films are reported. All the compositions exhibited B2-type structure with the actual composition of each film, as determined by Rutherford backscattering spectroscopy (RBS), being close to the nominal value. The values of saturation magnetization increase with increasing Mn content in the films and are in general agreement with the values obtained using the Slater–Pauling rule and the actual (RBS determined) compositions. Electrical resistivity as a function of temperature shows a change from metallic-type behaviour for x ⩽ 0.25 to a semiconducting type for x > 0.25. At lower temperatures (T < 25 K) metallic compositions show the presence of a resistivity minimum. The resistivity behaviour above low T upturn in metallic compositions follows a T 2 dependence that is explained in terms of electron–electron scattering and one-magnon scattering. The presence of a resistivity minimum and the crossover from metallic to semiconducting type resistivity are explained in terms of localization effects originating mainly in the Co antisite disorder in these alloy films.

We propose experimentally feasible schematics to teleport one of the major attributes of matter—i.e. atomic motion in the momentum space—with the assistance of Bragg regime atom-cavity field interactions. In this context, the procedure for teleportation of a superposition of the external momentum of a neutral atom along with its atomic momentum Bell state is described in detail. The protocol is then generalized to cover the teleportation of any high-dimensional entangled state. Such schematics based on a hybrid system—i.e. atoms and photons—may solve a long standing problem by efficiently closing both the detection as well as locality loopholes simultaneously for Bell’s inequality testing, an option not available with either photons or atoms alone.